1. Patho/Phys II
Neuro A&P Review

2. Nervous System CNS PNS Afferent (sensory) pathways
Patho/Phys II
Nervous System
CNS
Brain
Spinal cord
PNS
Cranial Nerves
Spinal Nerves
Afferent (sensory) pathways
Efferent (effector/motor) pathways

3. Peripheral Nervous System
Patho/Phys II
Peripheral Nervous System
Functionally
Somatic system
Autonomic system
Sympathetic
Parasympathetic

4. Nervous Tissue Neuron Supporting Cells Astrocytes (multiple roles)
Patho/Phys II
Nervous Tissue
Neuron
Supporting Cells
Astrocytes (multiple roles)
Oligodendria (form myelin in CNS)
Schwann cells (form myelin in PNS)
Microglia (CNS macrophage)
Ependymal (lines ventricles; forms CSF)

5. Patho/Phys II
Neuron

6. Patho/Phys II

7. Tracing the Neural Pathway
Patho/Phys II
Tracing the Neural Pathway
Dendrite receives stimuli
Initiates depolarization at cell body
Electrical impulse jumps from node to node on axon
At end of axon, reaches axon terminal
Terminal releases neurotransmitters.

8. Initiation of Neural Impulse
Patho/Phys II
Initiation of Neural Impulse
A single neuron may synapse with 50,000 other neurons
Each secretes a neurotransmitter or neuropeptide
Hundreds of possible chemicals
Some excitatory
Some inhibitory
Varying strength
Neuron must interpret this cacophony and decide...
To depolarize or not to polarize... that is the question

9. Nerve Injury and Regeneration
Patho/Phys II
Nerve Injury and Regeneration
Axon is severed
Distal to injury
Axon disintegrates
Myelin sheath unwinds into Schwann cells and line path
Proximal
Disintegration to the next node of Ranvier
Cell body swells
Begins to grow from stump of axon down Schwann path
Limited by scar tissue

10. Brain Cerebral cortex (“rind”) – gray matter Frontal Parietal Temporal
Patho/Phys II
Brain
Cerebral cortex (“rind”) – gray matter
Frontal
Parietal
Temporal
Occipital
Wernicke’s area – receptive aphasia
Broca’s area – expressive aphasia

11. Brain Basal ganglia: motor function Thalamus: relay station
Patho/Phys II
Brain
Basal ganglia: motor function
Thalamus: relay station
Hypothalamus: HR, BP, sleep, etc.
Cerebellum: motor coordination
Brain stem
Midbrain
Pons
Medulla: respiration, heart, GI function, CN

12. Meninges 3 membranes surrounding brain and spinal cord
Patho/Phys II
Meninges
3 membranes surrounding brain and spinal cord
Dura mater – 2 layers
Periosteum (next to cranium) (epidural space)
Inner dura (meningeal layer)
Subdural space between dura mater and next layer
Arachnoid membrane
Follows contours of brain but not sulci
Subarachnoid space between arachnoid and next layer
Pia Mater
Delicate, follows sulci and fissures

13. CSF and Ventricles Similar to plasma
Patho/Phys II
CSF and Ventricles
Similar to plasma
Circulates in ventricles and subarachnoid space (125 – 150 ml) at any one time
Brain floats in it
Cushions against jarring and jolting
Prevents pulling on meninges and blood vessels

14. Blood Supply Brain receives 20% of cardiac output
Patho/Phys II
Blood Supply
Brain receives 20% of cardiac output
Collateral circulation
Internal carotid
Vertebral arteries
Join in circle of Willis
Venous drainage
Does not parallel arterial supply
Venous plexuses and dural sinuses drain into internal jugular vein

15. Neurotransmitters Multipurpose Acetylcholine: multipurpose
Patho/Phys II
Neurotransmitters
Multipurpose
Depends on post-synaptic neuron and receptor type
Acetylcholine: multipurpose
Crosses neuromuscular junction of motor neurons
Released by both preganglionic sym & parasympa
Released by postganglionic parasympathetic fibers
Cholinergic fibers

16. Neurotransmitters Norepinephrine
Patho/Phys II
Neurotransmitters
Norepinephrine
Released by posganglionic sympathetic fibers
Adrenergic fibers
Released by adrenal glands
Function of catecholamines varies by receptor and tissue of receptor
α1 receptor most common
α2 receptor cause inhibition/relaxation
β1 heart and kidney
β1 all other beta receptors

17. Functions of Autonomic System
Patho/Phys II
Functions of Autonomic System
Generally
Sympathetic stimulation promotes protection of host
Increase BP, HR, glucose
Increase muscle blood flow and stimulation
Decrease renal flow and digestion
Parasympathetic stimulation promotes rest, tranquility and maintenance functions
Digestion
Secretion of enzymes
Action is often antagonistic

18. Aging Extremely complex How much is aging, and how much is disease?
Patho/Phys II
Aging
Extremely complex
How much is aging, and how much is disease?
Brain
Decreased weight and size
Increased adherence of dura mater to skull
Fibrosis of meninges
Widened sulci
Enlarged ventricles

19. Cellular Changes with Age
Patho/Phys II
Cellular Changes with Age
Decrease in number of neurons
Not consistent with cognitive loss
Implications and reason are unknown
Cellular changes
Dendrite changes
Lipofuscin deposition (Fatty deposits)
Neurofibrillary tangles (abnormal proteins)
Senile plaques (nerve degeneration)
Last two are accelerated in Alzeimer's
Changes is neurotransmitter function

20. Tests of Nervous Function
Patho/Phys II
Tests of Nervous Function
X-ray: primarily for bony structures
CT: 2-D recreation from multiple X-rays
Structures, tumors, hemorrhage (with or without contrast)
MRI: magnetic field; soft tissue analysis
MRA (angiography): visualization of blood vessels (stroke and TIA)
PET: injection of radioactive substances; detects positrons; indicates physiologic processes

21. Tests of Nervous Function
Patho/Phys II
Tests of Nervous Function
Brain scan: uptake of radioactive isotopes
Cerebral angiography
Myelography: x-ray with subarachnoid dye
Echoencephalography (ultrasound)
Electroencephalography (EEG): seizures
Evoked potentials
CSF analysis: protein, blood, organisms

22. Spinal Cord Nerve cell bodies arranged in “horns”
Patho/Phys II
Spinal Cord
Nerve cell bodies arranged in “horns”
Nerve pathways cross in the spinal cord
Eg. Sensation of the left side of the body enters the left dorsal horn, and crosses to the right ventral horn and travels to right hemisphere
Sensation
Spinothalamic tract: pain, temperature, crude and light touch
Posterior columms: does not cross sides; position, vibration, finely localized touch